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Caption: Spectrograph laser comb. Artwork of equipment needed for increasingly precise future spectroscopic analysis. This equipment is known as the laser comb, and will be used as a 'ruler' to calibrate spectrographs that will be used to search for Earth-like planets or measure the expansion of the Universe. Light from the Sun (upper left) is coupled to an optical fibre (wavy line) that guides it to a spectrograph (prism, lower right) that splits it into a spectrum (bottom) with spectral lines (dark peaks). The bright (white) spectral lines of the pulsed laser (also known as an astro-comb) help to filter the light and are used to calibrate the equipment.Restrictions: